Abstract:
The biodiversity of the seafloor community at Terra Nova Bay was investigated to determine the structural and functional diversity of the benthic community and to extend the latitudinal gradient survey beyond McMurdo Sound. Three dive sites were established in Tethys Bay in the 02-03 season. Two 20m transect lines were laid on the seafloor within the 15-25m depth stratum starting from haphazardly chosen starting points. The transects were videoed using a diver-held digital video camera at a fixed height of (a) 70cm above the bottom (for the broader scale analysis of habitat structure) and (b) 40cm above the bottom (to allow for more accurate species identifications). Along one of the 20m transects, core samples were collected from five randomly chosen positions. At each position, two small sediment cores (20mm diam., 50mm deep) were collected, one to determine sediment grain size and benthic chlorophyll a content and one to determine the natural stable isotope signature of carbon and nitrogen of the sediment. Also at each position, one large core (70mm diam., 100mm deep) was collected to estimate the abundance and diversity of the benthic macrofauna. Video sampling was stratified by habitat and additional footage was taken of biota in the study area for a general picture of the site. In addition to the survey work, a video sledge was used to survey deeper areas of the seafloor from the Malippo (Italian program boat). The sledge consisted of two frame-mounted high resolution colour CCD video cameras with independent light sources scaling lasers and depth/heading instrumentation. The equipment was towed along the seafloor behind the boat and its position recorded using GPS. The sledge was kept approx 1m above the seafloor. Two transects were surveyed running south of Faraglione in deep water (one at 50-80m, the other at 90-110m) and 10 locations along each video transect were sampled using a Van Veen grab. From each grab, 2 cores of sediment were collected (5cm diam, 10cm deep) to determine grain size, stable isotope signature and benthic chlorophyll concentration. In addition, a shallower area (30-40m) was surveyed nearer to Faraglione. In the 06-07 season two further locations, Gerlache Inlet and south of Tethys Bay were survey with the above methods. The effects of disturbance by anchor ice on epibenthic flora and fauna was investigated at south Tethys Bay also and remote video sampling was conducted in the wider Terra Nova bay area to allow a more general picture of the benthos of the region to be developed.